Capacitive sensing is a technology based on capacitive coupling which takes human body capacitance as input. Capacitive sensing is used in many different types of sensors, including those to detect and measure proximity, position or displacement, humidity, fluid level, and acceleration. Capacitive sensing as a human interface device (HID) technology (for example, to replace the computer mouse) has become more popular. Capacitive touch sensors are used in many devices such as laptop trackpads, digital audio players, computer displays, mobile phones, mobile devices, tablets etc. Design engineers continue to choose capacitive sensors for their versatility, reliability and robustness, unique human-device interface, and cost reduction over mechanical switches.
Capacitive sensors generally detect anything that is conductive or has a dielectric different than that of air. While capacitive sensing applications can replace mechanical buttons with capacitive alternatives, other technologies such as multi-touch and gesture-based touchscreens are also premised on capacitive sensing.
In a separate endeavor, mobile devices have surpassed the standard desktop computer. A mobile device can take the form of, for example, a tablet, a smartphone (inclusive of Android™ phones, i-Phones™), an i-Pad™, a Google Nexus™, a Microsoft Surface™, a personal computer, a video processing component, a laptop computer (inclusive of any type of notebook), any type of touch-enabled input device, a portable media platform (PMP), etc. Some mobile devices are powered by a battery, and some mobile devices are capable of being powered by an external power source such as an alternating current (AC) outlet. Many mobile devices support wired and/or wireless communication for telephony, video conferencing, and/or data transfer.
Mobile devices can be used in a variety of environments. For example, a user can hold a mobile device to his ear or at arm's length. Mobile devices can be placed on a surface such as a table, desk, or counter. A user can place a mobile device in an enclosed space such as a drawer, purse, or pocket. Some mobile devices can be equipped with a protective case. Some mobile devices can be placed in a stand or docking station, which can facilitate charging or wired communication with another device.
The environment around a mobile device may change over time. For example, the mobile device may be moved between environments (such as from a table to a purse). People or objects may move in the vicinity of the mobile device. Atmospheric conditions in the vicinity of the mobile device can change. For a variety of reasons, it can be desirable to ascertain environmental conditions in the immediate vicinity of a mobile device.